1. Field of Invention
The invention relates to an integrally formed helmet and the manufacturing method thereof. In particular, the invention relates to a safety helmet for bicycle or car racing and the manufacturing method thereof.
2. Related Art
Current safety helmets for bicycle or car racing are roughly the same in their structures. The outer shell is usually hard and made of compound materials such as PC, ABS, carbon fibers, glass fibers, and kevlar. In the hard shell is filled with a light and soft material layer that is in direct contact with the user's head. When a collision occurs, the soft inner shell is responsible for absorbing the impact.
The manufacturing method for the above-mentioned safety helmet involves filling Styrofoam particles inside the outer shell, followed by heating and pressing them to form an inner shell. The outer surface of the Styrofoam shell is then taped and attached onto the outer hard shell. The inner surface of the Styrofoam shell is decorated with a soft cotton layer so that the head is not in direct contact with the rough Styrofoam and the Styrofoam surface is also protected. However, the procedure is complicated and more expensive.
Moreover, the hard outer shell and the Styrofoam inner shell are often connected by buckle belts. It is very likely to have a gap between and thus for them to separate from each other. In a collision, the impact is not uniformly distributed to effectively protect the user's head.
If the hard outer shell is made of compound materials such as carbon fibers, glass fibers, and kevlar, it is usually formed by coating a resin on a synthetic fiber cloth. This results in a larger space between fibers. The use of resin also increases the overall weight.
The above-mentioned techniques have been disclosed in PROC Pat. Nos. 93104671.8, 95115447.8, and 03825759.9.